1. Technical Field
The present invention relates to an image display device and a method of controlling the image display device.
2. Related Art
As a configuration of a display device for displaying an image such as a content, there has been known a projector, which modulates a light emitted from a light source in accordance with an image signal using a light modulation device, and then projects the modulated light on a screen or the like in an enlarged manner to display the image. Such a light modulation device is formed of liquid crystal light valves or the like provided with a plurality of pixels, and controls the transmittance of the light pixel by pixel in accordance with the grayscale information represented by the image signal to thereby form the image corresponding to the image signal.
In resent years, there has been proposed a projector provided with an expansion device for correcting the grayscale (the transmittance) of each of the pixels in order to expand the effective grayscale range, and a dimming device capable of roughly evenly reducing the intensity of the light entering each of the pixels of the light modulation device in accordance with the correction as described in JP-A-2012-32583. According to this configuration, it becomes possible to increase the number of the effective grayscales (expand the dynamic range) to improve the contrast feel by performing an adaptive dimming process, namely reduction of the light intensity by the dimming device and the expansion of the grayscale range by the expansion device based on a feature amount of the image, when displaying, for example, a dark image.
Incidentally, it is known that the projector used in a cool environment has the liquid light valves or the like disposed inside also in a cool state, takes time from when the projector is started until the inside is warmed by the energy of the light emitted from the light source, and is slow in response speed of the liquid crystal in a period until the liquid crystal light valves are heated to a predetermined temperature, and has the display quality degraded. Therefore, it is desirable that the liquid crystal light valves in the cool state are rapidly warmed when the projector is started up.
However, in the case of starting up the projector in the cool environment to start the projection of the image, the adaptive dimming process is performed in accordance with the luminance of the image, and the light intensity is decreased by the dimming device if the image is dark, and therefore, it takes time to warm the liquid crystal light valves. Therefore, the period for performing the projection in the state in which the display quality is degraded is long at the time of start up compared to the case in which the light intensity is not reduced, and in some cases, uncomfortable feeling is provided to the observer.